set_hardware_volume

Description

Alters the hardware sound output volume. Specify volumes for both digital
samples and MIDI playback, as integers from 0 to 255, or pass a negative
value to leave one of the settings unchanged. Values bigger than 255 will
be reduced to 255. This routine will use the hardware mixer to control the
volume if it exists (i.e. the volume of all the applications on your
machine will be affected), otherwise do nothing.